cairodriver/raster.c

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/*!
   \file lib/cairodriver/raster.c
 
   \brief GRASS cairo display driver - draw raster
 
   (C) 2007-2014 by Lars Ahlzen and the GRASS Development Team
 
   This program is free software under the GNU General Public License
   (>=v2). Read the file COPYING that comes with GRASS for details.
 
   \author Lars Ahlzen <lars ahlzen.com> (original contributor)
   \author Glynn Clements
 */
 
#include <math.h>
 
#include "cairodriver.h"
#include <grass/gis.h>
#include <grass/glocale.h>
 
#define MAX_IMAGE_SIZE 32767
 
static int src_t, src_b, src_l, src_r, src_w, src_h;
static int dst_t, dst_b, dst_l, dst_r, dst_w, dst_h;
 
static int *trans;
 
static cairo_surface_t *src_surf;
static unsigned char *src_data;
static int src_stride, ca_row;
 
static int masked;
 
static double scale(double k, int src_0, int src_1, int dst_0, int dst_1)
{
    return dst_0 + (double)(k - src_0) * (dst_1 - dst_0) / (src_1 - src_0);
}
 
static int scale_fwd_y(int sy)
{
    return (int)floor(scale(sy, src_t, src_b, dst_t, dst_b) + 0.5);
}
 
static int scale_rev_x(int dx)
{
    return (int)floor(scale(dx + 0.5, dst_l, dst_r, src_l, src_r));
}
 
static int next_row(int sy, int dy)
{
    sy++;
 
    for (;;) {
        int y = scale_fwd_y(sy);
 
        if (y > dy)
            return sy - 1;
        sy++;
    }
}
 
/*!
   \brief Start drawing raster
 
   \todo are top and left swapped?
 
   \param mask non-zero int for mask
   \param s source (map) extent (left, right, top, bottom)
   \param d destination (image) extent (left, right, top, bottom)
 */
void Cairo_begin_raster(int mask, int s[2][2], double d[2][2])
{
    int i;
    cairo_status_t status;
 
    masked = mask;
 
    src_l = s[0][0];
    src_r = s[0][1];
    src_t = s[1][0];
    src_b = s[1][1];
 
    src_w = src_r - src_l;
    src_h = src_b - src_t;
 
    dst_l = (int)floor(d[0][0] + 0.5);
    dst_r = (int)floor(d[0][1] + 0.5);
    dst_t = (int)floor(d[1][0] + 0.5);
    dst_b = (int)floor(d[1][1] + 0.5);
 
    dst_w = dst_r - dst_l;
    dst_h = dst_b - dst_t;
 
    G_debug(
        1,
        "Cairo_begin_raster(): masked=%d, src_lrtb=%d %d %d %d -> w/h=%d %d, "
        "dst_lrtb=%d %d %d %d -> w/h=%d %d",
        masked, src_l, src_r, src_t, src_b, src_w, src_h, dst_l, dst_r, dst_t,
        dst_b, dst_w, dst_h);
 
    /* create source surface */
    src_surf =
        cairo_image_surface_create(CAIRO_FORMAT_ARGB32, ca.width, ca.height);
    status = cairo_surface_status(src_surf);
    if (status != CAIRO_STATUS_SUCCESS)
        G_fatal_error("%s - %s - size: %dx%d (cairo limit: %dx%d)",
                      _("Failed to create cairo surface"),
                      cairo_status_to_string(status), ca.width, ca.height,
                      MAX_IMAGE_SIZE, MAX_IMAGE_SIZE);
 
    src_data = cairo_image_surface_get_data(src_surf);
    src_stride = cairo_image_surface_get_stride(src_surf);
    ca_row = 0;
 
    /* allocate buffer for down-sampling data */
    trans = G_malloc(dst_w * sizeof(int));
    for (i = 0; i < dst_w; i++)
        trans[i] = scale_rev_x(dst_l + i);
}
 
/*!
   \brief Draw raster row
 
   \param n number of cells
   \param row raster row (starting at 0)
   \param red,grn,blu,nul red,green,blue and null value
 
   \return next row
 */
int Cairo_raster(int n, int row, const unsigned char *red,
                 const unsigned char *grn, const unsigned char *blu,
                 const unsigned char *nul)
{
    int d_y0 = scale_fwd_y(row + 0);
    int d_y1 = scale_fwd_y(row + 1);
    int d_rows = d_y1 - d_y0;
    int x0 = MAX(0 - dst_l, 0);
    int x1 = MIN(ca.width - dst_l, dst_w);
    int y0 = MAX(0 - d_y0, 0);
    int y1 = MIN(ca.height - d_y0, d_rows);
    int x, y;
 
    if (y1 <= y0)
        return next_row(row, d_y1);
 
    G_debug(3, "Cairo_raster(): n=%d row=%d", n, row);
 
    for (x = x0; x < x1; x++) {
        int xx = dst_l + x;
        int j = trans[x];
        unsigned int c;
 
        if (masked && nul && nul[j])
            c = 0;
        else {
            unsigned int r = red[j];
            unsigned int g = grn[j];
            unsigned int b = blu[j];
            unsigned int a = 0xFF;
 
            c = (a << 24) + (r << 16) + (g << 8) + (b << 0);
        }
 
        for (y = y0; y < y1; y++) {
            int yy = d_y0 + y;
 
            *(unsigned int *)(src_data + yy * src_stride + xx * 4) = c;
        }
    }
 
    ca.modified = 1;
    ca_row++;
 
    return next_row(row, d_y1);
}
 
/*!
   \brief Finish drawing raster
 */
void Cairo_end_raster(void)
{
    G_debug(1, "Cairo_end_raster()");
 
    /* paint source surface onto destination (scaled) */
    cairo_save(cairo);
    /* cairo_translate(cairo, dst_l, dst_t); */
    /* cairo_scale(cairo, dst_w / src_w, dst_h / src_h); */
    cairo_surface_mark_dirty(src_surf);
    cairo_set_source_surface(cairo, src_surf, 0, 0);
    cairo_pattern_set_filter(cairo_get_source(cairo), CAIRO_FILTER_NEAREST);
    cairo_paint(cairo);
    cairo_restore(cairo);
 
    /* cleanup */
    G_free(trans);
    cairo_surface_destroy(src_surf);
    ca.modified = 1;
}